First, Playboy and other print pornography were available long before VHS and Betamax. Is the claim that video pornography is the key product which reduced sexual violence?

Second, what fraction of young men regularly viewed pornography on videotape from 1975-1990? It has to be much, much lower than the (near-ubiquitous) viewing of online pornography today. (Then again, maybe those most at risk to commit sexual violence were much more likely to purchase pornography on video.)